KR20000024688A - Vertical-type minute probe card - Google Patents

Abstract

PURPOSE: A probe card is provided to mount probes arranged evenly and precisely on a flat substrate to measure electric characteristics of plural semiconductor devices. CONSTITUTION: An insulation substrate(1) is fixed on a circuit substrate. plural protrudedprobes(2) having elasticity are fixed on the insulation substrate(1). Conductive wiring is formed according to a design from the probes(2) and to the circuit substrate through the insulation substrate(1). The probes(2) are manufactured in a manner which a pattern is defined by a photo lithography and necessary portions are remained by means of dry etching. Ends of the probes(2) are contacted with a particular contact of a to-be-measured device. The probes(2) are connected to the contacts of the insulation substrate(1), respectively.

Description

Vertical Fine Probe Card

The present invention relates to a structure of a vertical probe card, which is a type of probe card used for electrical inspection in the manufacture of small electronic devices, and a method of manufacturing the same. Conventional probe cards have large and long probes, which limit the number and location of the probes, and have poor electrical characteristics. The goal of developing a new type of probe card is to install a larger number of probes than conventional methods, while keeping the size of the probe constant so that the electrical properties are improved.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of probe cards for measuring the electrical properties of electronic devices fabricated in semiconductor wafers and the like.

When fabricating an electrical circuit device, such as a semiconductor integrated circuit device, its overall or partial electrical properties during or after the fabrication process of the device and prior to attaching a lead frame. Test to see if it matches the design. The equipment used for this test is a probe station, the schematic of which is shown in FIG. 5A. This equipment is equipped with a probe card, which is a device for measuring various electrical signals in a probe device and electrical contacts on a single or plural elements formed on a semiconductor wafer to be measured. It plays a role of connecting the pads. The structure of a probe card consists of two parts. One is a circuit board 12 that structurally supports the probe and forms a circuit connecting the probe with the probe, and the other is a probe 13 mounted on the substrate, which is shown in FIG. 5B. It directly contacts the element to be measured 6.

The probe card is attached to the underside of the insertion ring which is supported by a HEAD PLATE 10 on the outside of the probe equipment. The work shelf 14 is located under the probe card, and the work shelf is made to move in three dimensions in the horizontal direction (X, Y axis direction) and vertical direction (Z axis direction). The element to be measured 6 is placed on the work shelf.

The measurement begins by first fixing the element to be measured to the working shelf. The work shelf is then moved in the X and Y axis directions so that the probe of the probe card and the contact 5 of the element to be measured coincide. Then, it moves in the Z-axis direction so that contact between the probe and the contact point 5 of the element to be measured occurs. The probe equipment then generates an electrical signal for measuring the electrical properties of the device, which is transmitted via a pogo pin 11 to the circuit board 12 of the probe card. This signal travels from the circuit board to the probe and from the probe to the device to be measured via electrical wiring from the circuit board to the tip of the probe 13. The electrical response signal from the device then travels in the reverse order to the probe equipment.

The existing scheme shown in FIG. 5 is referred to as the horizontal type or tungsten needle scheme. In this method, a tungsten needle 13 having a sharp tip is fixed to a frame, and its tip is brought into contact with the contact point 5 of the element to be measured, and measurement is performed. However, in recent years, the electrical contacts of semiconductor devices have become very small, and there are cases in which dozens of contacts are arranged per device at intervals of several micrometers. Therefore, in the conventional method, the thickness of the tungsten needle is hundreds of micrometers, so it is difficult to install as many needles as necessary to measure multiple devices simultaneously. In addition, it is difficult to install the needle to exactly contact the specific position of the minute contact. In addition, the length of the probe is long, and the length of each probe is different, it is easy to mutual interference and difficult to adjust the impedance when sending an electrical signal. Therefore, they cannot be used to measure devices that operate at high speeds, such as Rambus Dynamic Random Access Memory.

The vertical method was developed to improve these points. In the vertical method, since a small number of probes are arranged on a substrate, a large number of probes can be arranged at narrow intervals, and the length of the probe is also short, so the electrical characteristics of the manufactured probe card are excellent.

An important point in the manufacture of the vertical probe is that all installed probes must be in contact with the electrical contacts (Pad) of the device under measurement. In addition, each probe must press the contacts with a pressure above a certain value. For this purpose, the tip of the manufactured probe is very uniformly arranged so that the flatness is excellent and each probe has a certain degree of elasticity. If the probe is elastic and can cause elastic deformation, if there is a slight error in the flatness of the tip of the probe or an error in the position of the contact point of the device to be measured, for example, the semiconductor wafer on which the device is formed is not completely flat. Even with minor distortions, the probe card can be used to make the required electrical measurements. Publications of this new type of probe are disclosed in US Pat. No. 4,961,052, US Pat. No. 5,172,050, and US Pat. No. 5,723,347.

The present invention is to fabricate a vertical probe having the required mechanical properties, for example, an appropriate elastic deformation and mechanical strength, and to produce a probe card in which the probe is densely attached to a suitable position on a substrate. Probes attached to the probe card shall be able to contact the electrical contacts of the device under test and measure the electrical properties of the device under test.

There should be no leakage current between the probe and the probe. In addition, the probe shall be restored to its original shape after measurement and free of deformation during the specified life of the card (eg 300,000 contacts).

1 is a perspective view of the entire assembly

Figure 2a is a side view of the fabricated device

Figure 2b is a side view of the elastically deformed shape when the fabricated device is used

Figure 3a is a side view attached to the insulating substrate after the first etching

Figure 3b is a side view of the etching completed after bonding to the insulating substrate

Figure 4 is one way of connecting the wiring

5A is a schematic diagram of a probe device according to the prior art

5b is an enlarged perspective view of a probe portion of a probe device according to the prior art;

Symbol description in drawings

1: insulation board

2: main body of the probe

3: tip of the probe

4: electrical wiring

5: Contact point of the element to be measured

6 element to be measured

7: cavity formed during the fabrication of the probe

8: electrode connected to the probe

9: gold wire bonded to the probe by wire bonding method

10: probe equipment headboard

11: pogo pin

12: circuit board

13: tungsten needle

14: working lathe

1 is one example of applying the present invention. The probe card is manufactured by forming an elastic probe (2) on the insulating substrate (1), joining a hard material (3) to the tip of the probe, and then forming a wiring (4). Although only two probes are shown in FIG. 1, thousands or more probes may be formed as necessary. 2A is a side view of FIG. 1. The element 6 to be measured has a contact 5 thereon. At this time, the work shelf on which the measurement target element is mounted is moved upward, or the head plate fixing the probe is lowered, and the contact 5 and the tip 3 of the probe come into contact with each other, thereby causing the probe to elastically deform as shown in FIG. 2B. After that, the electrical measurement proceeds, and after completion of the measurement, the probe is restored to a circular shape as shown in FIG. 2A.

The general manufacturing method is as follows.

After the pattern is defined using photolithography on a probe material with the required elasticity and hardness (for example, single crystal silcon wafer), wet etching or dry etching ( dry etching) to remove unnecessary parts of the probe material. The probe material partially etched into the substrate (e.g. glass, ceramic), which has the required elasticity and hardness, is then subjected to an appropriate bonding method, e.g. fusion bonding or electrical bonding. Bond using (anodic bonding). The probe is then formed again by removing unnecessary portions of the probe material several times using wet etching or dry etching. On top of that, the electrical circuits are deposited using a method of depositing an electrically conductive layer and an electrical sub-layer, such as sputtering, evaporation, or chemical vapor deposition (CVD), and optical lithography and etching. Configure. The constructed circuit includes wiring grounded at an appropriate position to minimize electrical interference, and if necessary, an insulating film and a conductive film may be formed above or below the circuit portion. A material having a high hardness, for example, a tungsten film, may be deposited on the tip 3 of the probe manufactured as shown in FIG. Alternatively, the tip of the probe can be made separately from tungsten and attached to the probe by welding.

Detailed examples of the practical manufacturing method of the present invention are as follows.

Silicon oxide thin film or silicon nitride thin film is deposited on a silicon wafer with a <110> crystallographic direction polished on both sides by thermal CVD, physical vapor deposition (PVD), plasma assisted chemical vapor deposition (PECVD), etc. It is deposited using the method of, and the pattern is defined and etched by using optical lithography, and used as a mask for silicon etching. The silicon layer is etched vertically to a depth between 5 and 500 micrometers using anisotropic wet etching using KOH solution. In this case, the etching depth may be larger or smaller than the height of the probe tip, which will be described later, but it is advantageous to be smaller than the height of the probe in order to eliminate the possibility of other parts except the tip of the probe touching the device to be measured. Thereafter, the etched side of the silicon is brought into contact with a glass substrate, and a temperature of 300 to 600 degrees Celsius is applied by applying a pressure between 1 and 5 atm to fusion bonds. Alternatively, the temperature may be raised between 200 degrees Celsius and 500 degrees Celsius, and then an electric bond may be applied by applying a voltage between 100 V and 2000 V to allow a current of 1 mA to 10 mA to flow. The side shape of the device being manufactured immediately after the bonding is shown in FIG. 3, and the etched portion 7 is left in the empty space. After bonding, if the thickness of the bonded silicon is more than necessary, polishing is carried out to adjust the required thickness. The required thickness is determined by the size of the probe being manufactured. Then, a silicon oxide thin film or silicon nitride thin film is deposited on the bonded silicon by thermal decomposition chemical vapor deposition, physical vapor deposition, plasma enhanced CVD, etc., and the pattern is defined and etched by optical lithography. . Etched silicon oxide thin film or silicon nitride thin film is used as a mask for silicon etching, and anisotropic wet etching method using KOH solution is used to vertically remove the silicon layer to a depth of 5 to 500 micrometers. To produce cutting edges. Then, the bonded silicon oxide thin film or silicon nitride thin film is deposited using a thermal decomposition chemical vapor deposition method, physical vapor deposition method, plasma assisted chemical vapor deposition method, etc., and the pattern is defined and etched using optical lithography to form a silicon etching mask. By using an anisotropic wet etching method using a KOH solution to produce the body of the probe, ie the lever portion, by vertically etching the silicon layer to a depth between 5 and 500 micrometers. In order to increase the electrical conductivity of the manufactured probe, a process of adding boron or phosphorus to the silicon probe by ion implantation or heat treatment may be performed. Subsequently, wiring is formed from the tip of the probe to a predetermined portion of the insulating substrate by using a conductor deposition method such as sputtering, evaporation, or chemical vapor deposition and optical lithography. The wiring can be formed on the surface on which the probe of the insulating substrate is provided, or on the opposite side, or can be formed in multiple layers through or inside the insulating substrate. The completed insulation board with the fabricated probe is bonded to the circuit board. At this time, there are various methods of connecting the wiring formed on the circuit board and the insulating board, but two examples are shown in FIGS. 4A and 4B. FIG. 4A illustrates a method of connecting a wire by forming a hole penetrating an insulating substrate and filling a conductor therein. In FIG. 4B, a probe is formed to form a wire on a surface of an insulating substrate, and wire bonding is directly performed on the wire.

When the present invention is applied, a probe having a very uniform height and very precisely arranged can be installed on a flat substrate, and thus a probe card capable of simultaneously measuring electrical characteristics of a plurality of semiconductor devices can be manufactured.

Another effect of the present invention is that it is possible to manufacture a probe card having excellent electrical properties because the length of the probe is short and the size of each probe is constant.

Another effect of the present invention is that when the manufactured probe is made of single crystal silicon, it has very excellent elastic properties and restoring force, so that plastic deformation does not occur during use, thereby extending the life of the probe card.

Claims (10)

1. A probe card in which a plurality of probes are arranged and fixed in a manner consistent with a contact (pad or bonding pad) of a device to be measured; An electrically insulated insulating substrate is fixed on the circuit board, and a plurality of elastically protruding probes are fixed on the insulating substrate, and conductive wiring is formed according to the design from the probe to the circuit board through the insulating substrate. The probe is manufactured in such a way that the pattern is defined by the optical lithography method, leaving only the necessary parts by etching method.The tip of the probe is in contact with one specific contact point of the device to be measured, and the insulating substrate is more than a certain degree. A probe card that is constructed so that the deformation is stopped before the probe reaches the elastic deformation limit by limiting the deformation, and each probe is connected to each contact on the insulating board and connected to the probe card at this contact. The probe card of claim 1 wherein the probe is comprised of single crystal silicon. The probe card according to claim 2, wherein the probe card is fabricated using ion implantation or impurity implantation by thermal diffusion into single crystal silicon for the purpose of improving the electrical conductivity of the probe. The probe card of claim 1, wherein the probe is fixed to an insulating substrate by melting or electrolytic bonding. The probe card of claim 1, wherein glass or ceramic is used as the insulating substrate. The probe card of claim 1, wherein the probe is manufactured by using wet etching or dry etching together with an optical lithography method. The probe card of claim 6, wherein the probe is manufactured by performing dry etching by reactive ion etching or isotropic dry etching. The probe card according to claim 1, wherein the electrically conductive wiring is deposited by sputtering, chemical vapor deposition, or sublimation deposition, and a pattern is formed using an optical slab method and an etching or lift-off method. The probe card of claim 1, wherein the probes are structurally and electrically separated from each other and bonded to a substrate having a material different from that of the probe material. The probe card of claim 1, wherein the tip of the probe is plated with tungsten or tungsten silicide, or the whole tip is made of tungsten and attached to the probe.